X-bit labs - Print version

While we were waiting impatiently for the new AMD Athlon XP Barton with 400MHz bus, we decided to take a look at the new ABIT NF7 2.0 mainboard to check how well Barton performs with this processor bus and how greatly its performance grows when the PSB speed increases.

It is almost an evident fact that Athlon XP processors will soon move to 400MHz bus. That is why it is not at all surprising that the chipset and mainboard manufacturers are willing to get ready for this event in advance. When AMD announces its new Athlon XP with 400MHz bus, there should be enough chipsets and mainboards in the market capable of working with these processors. All three leading Socket A core logic developers prepared very well for the launch of the new processors and have new chipsets at hand now. They are: VIA KT600, SiS748 and NVIDIA nForce2 Ultra 400. The mainboard manufacturers run neck and neck with the chipset guys and do their best to release new mainboards with 400MHz bus support as early as possible.

In fact the first mainboard manufacturer, who announced the availability of products compliant with 400MHz bus of the upcoming Athlon XP processors, appeared ABIT Company. The first mainboard from ABIT working stably and faultlessly with the CPUs supporting this bus turned out NF7 (NF7-S) Rev. 2.0 based on the enhanced NVIDIA nForce2 chipset. So, we decided to return to ABIT NF7 mainboard (as you remember, we have already reviewed it, check our article ABIT NF7-S Mainboard: Overclocker’s Dream? for more details). In this article we will take a closer look at the new mainboard revision and will try to model the way this mainboard will work with the upcoming processors.

ABIT NF7 2.0: What’s New?

We have already taken a close look at one of the earlier ABIT NF7 revisions (see the review here). The new Rev. 2.0 of the legendary ABIT NF7 is certainly similar to the earlier revisions, however, it still boasts a number of remarkable peculiarities. Here I am going to dwell on these peculiarities.

The major difference between ABIT NF7 2.0 and the older revisions is the new NVIDIA nForce2 chipset stepping officially supporting 200MHz FSB (400MHz bus). The mainboard package says it very clearly:

Many of you who have older ABIT NF7 revisions may object to this saying that their mainboards also work perfectly well with 400MHz bus frequency, even though they are based on the older NVIDIA nForce2 chipset version. It would be true. Starting from the very first Rev. 1.0, all NF7 mainboards did allow increasing the FSB frequency up to 200MHz and higher and remained very stable working in this mode. But despite this fact, the actual state of things is not quite correct. In reality only those Athlon XP processors were working properly with 400MHz bus, which were based on Thoroughbred core. As we saw during our tests, Athlon XP processors on Barton core didn’t work stably on earlier revisions of ABIT NF7. The problem was inside the chipset.

Now NVIDIA is shipping new nForce2 chipset stepping, which will be officially known as nForce2 Ultra 400 and will support any Socket A processors with 400MHz bus.

Ultra stands for dual-channel, 400 – for 400MHz bus support.
There will also be a single-channel nForce2 400 chipset.

The NVIDIA nForce2 Ultra 400 will be officially announced together with the Athlon XP processors supporting 400MHz bus. So, there is not so much waiting left now.

New nForce2 Ultra 400 revisions are marked anew.
The first nForce2 officially supporting 400MHz bus is marked as A1.

As you can see from the photo, it is very easy to distinguish between the old chipsets and the new ones with the official support of 400MHz bus, even though there is no Ultra 400 marking. For example, NVIDIA doesn’t use the metal cover for the chipset anymore, which used to be typical of older nForce2 SPP.

This way, the major distinguishing feature of ABIT NF7 2.0 from the earlier board revisions is the full official support of Socket A processors with 400MHz bus. In fact, this is why ABIT NF7 2.0 uses a new BIOS version.

Besides the newer chipset used in the today’s ABIT NF7 2.0, which allows ABIT to claim that their product is compatible with the CPUs supporting 400MHz bus, there is a number of other peculiarities, which distinguish it from the predecessors (in fact, they appeared in Revision 1.2 already):

Although there are fewer capacitors now,
the mainboard retained its high stability.

This way, ABIT NF7 2.0 has now become even better for Socket A processors overclocking.

Overclocking

Well, let’s check how high we can raise the FSB frequency on ABIT NF7 2.0. in this test we will see how the PCB design change and the new chipset version affected the overclocking potential of this mainboard. In this case we were mostly interested in overclocking the mainboard in the maximum performance mode that is when the FSB and the memory worked synchronously. Moreover, the memory worked in dual-channel mode. The nForce2 based mainboards are known to be showing their maximum performance in this particular situation, however, the working frequencies are not as high as in asynchronous mode. For example, in our previous test session of ABIT NF7 Rev. 1.0 we managed to increase the FSB and memory frequencies only up to 212MHz.

Today we used a very well-overclockable Athlon XP 1700+, with the clock multiplier set to 8x. Like in the previous cases we didn’t modify the mainboard in any way, the chipset voltage was equal to 1.6V, the Vcore and Vdimm remained nominal. After a set of long-lasting experiments with the FSB frequency we managed to overcome the previous record. The FSB frequency, which we achieved this time without losing stability equaled 225MHz, which makes 450MHz of the effective frequency taking into account the DDR protocol of Athlon XP bus. Not bad, really.

400MHz Bus by Athlon XP: Soon Officially

Let’s have a look at the processor market today and find out what’s going on over there. At present the fastest Intel Pentium 4 processor for the desktop segment reached the top of 3GHz, these CPUs feature 512KB of L2 cache memory, support 800MHz bus and Hyper-Threading technology. The today’s Pentium 4 CPUs are based on Northwood core manufactured with 0.13micron copper interconnect technology. The competing product from AMD, Athlon XP 3000+, works at the actual frequency of 2.167GHz, features 512KB L2 cache and supports 333MHz bus. The top Athlon XP models are based on Barton core manufactured with 0.13micron copper interconnect technology. However, despite pretty diverse features sets both processors do not differ too much in performance in real applications. The thing is that both rivals, Pentium 4 and Athlon XP, boast very different architecture. These processors feature different number of execution units and different pipelines that is why it is absolutely impossible to compare these CPUs with one another from the working frequency point of view.

The nearest future looks almost the same for both CPU makers. Northwood core, as well as Barton, have almost reached their top clock frequency. Both, AMD and Intel, will be able to launch only one more CPU model working at a higher clock rate, which will be based on 0.13micron cores. Within the next month or two we will see the new Pentium 4 3.2GHz on Northwood core and Athlon XP 3200+ on Barton core.

According to the initial plan, in the beginning of April AMD was going to launch the first processors from the first 64bit desktop processor family: Athlon 64. Due to their enhanced architecture, integrated memory controller and the ability to process 64bit code, Athlon 64 processors could become very popular among computer enthusiasts if they were available in the market (for more details and indepth tests of the real Athlon 64 processor see our exclusive article AMD Athlon 64 Performance Preview). The launching of Athlon 64 could easily shake Intel’s positions in the desktop market that is why the microprocessor giant had to resort to retaliatory measures aimed at speeding up their CPUs. Since the currently used Northwood core features limited potential in terms of clock frequency increase, Intel decided to go another way. First they introduced Hyper-Threading technology in Intel’s top processor models. This technology allowed using processor resources more efficiently due to the opportunity to process two threads simultaneously. Then Pentium 4 was transferred to 800MHz bus. As a result, its performance grew up a little bit.

However, AMD’s initial plans, which pushed Intel to these active measures never came true. At the very last moment AMD postponed the launch of their Athlon 64 processors from spring 2003 to fall 2003. This relatively strange (at first glance) decision was made because AMD had faced some technological problems. Although the yields for AMD Athlon 64 were quite high, the top clock frequency of the CPUs hardly exceeded 2GHz, so that the performance of the new solutions couldn’t exceed that of the currently available Athlon XP processors. To increase the core frequency AMD is now working on a new Athlon 64 core revision, while Athlon XP Barton will have to defend AMD’s current position in the processor market.

This way, it turned out that the expected announcement of Athlon 64 pushed Intel to speed up its Pentium 4 processors, however, the change in AMD’s plans put the today’s Athlon XP on Barton core in a very difficult situation: they will have to compete with an enhanced Pentium 4. In this case, AMD has to follow into Intel’s footsteps and to resort to all sorts of tricks to increase its processors’ performance without increasing the core clock frequency, because it has almost reached the possible maximum. The easiest way to do this without redesigning the Athlon XP processor core is to raise the bus frequency. This will be exactly the move AMD is going to make within this month.

According to our info, the next Athlon XP 3200+ processor will work at 2.2GHz and will use 400MHz bus. This CPU will compete with Intel Pentium 4 3.2GHz with 800MHz bus and Hyper-Threading technology, which is due a little bit later. Besides Athlon XP 3200+, there will be one more processor to support 400MHz bus – Athlon XP 3000+. This CPU will work at the actual frequency of 2.1GHz, according to our preliminary data, which is 66MHz lower than Athlon XP 3000+ with 333MHz bus.

The transition of Socket A processors to 400MHz bus will allow using the DDR400 SDRAM more efficiently. This memory type has already been approved by Intel. So, as soon as Socket A systems acquire 400MHz bus support, it will also be used with them in synchronous mode, which will improve the performance. Since DDR400 SDRAM has already become pretty widely spread, the transition of Athlon XP to faster 400MHz bus is absolutely justified. Moreover, the constant improvement of memory production technologies allow the today’s DDR400 modules to work stably with quite aggressive timings, which are at least not worse than those of the average DDR333 SDRAM modules.

For example, Corsair Company, whose memory modules are truly considered to be among the best, is already shipping DDR400 modules working stably with 2-2-2-6 timings at 400MHz.

Corsair Company provided their TWINX512-3200LL memory modules set for us to test the mainboards based on nForce2 Ultra 400 with 400MHz bus. This set including two 256MB DDR400 SDRAM modules, which were preliminarily tested in dual-channel configurations, does work well at 400MHz with 2-2-2-6 timings and 2.6V Vdimm in the mainboards based on the new nForce2 stepping. We should also stress that these low timings are a great achievement for 400MHz working frequency. For example, we saw in our previous tests that even PC3700 memory modules, which can work at 450MHz, can run stably at 400MHz only with 2-3-3-6 timings.

This way, everything seems to be ready for Athlon XP processors to finally move to 400MHz bus. The chipsets and mainboards supporting Athlon XP on Barton core with 400MHz bus as well as high-speed memory modules are already available. Now there is only one thing everybody is waiting for: AMD should announce Athlon XP 3200+ and Athlon XP 3000+ for 400MHz bus.

Testbed and Methods

With a complete set for modeling the performance of the upcoming Socket A systems with 400MHz bus at our disposal, we couldn’t help playing with it a little bit. Therefore, we decided to take a closer look at the performance heights the upcoming Athlon XP 3000+ and 3200+ processors with 400MHz bus will be able to achieve. For this purpose we took the already described above ABIT NF7 2.0 mainboard, which works perfectly well with AMD Athlon XP (Barton) processors at 200MHz FSB frequency, and the Corsair TWINX512-3200LL memory modules set.

As for the Barton based CPUs, which could work at 2.1GHz and 2.2GHz, there were no problems here. The matter is that contemporary Athlon XP on Barton core can get easily overclocked up to 2.2GHz, as we have already discovered in our article called “AMD Athlon XP 3000+, 2800+ and 2500+ on Barton Core”. Moreover, it is true not only for the fastest Barton processor rated as 3000+, but also for the slower ones rated as 2500+ and 2800+. No wonder, really. The working frequency of the fastest model with 333MHz bus is just a little lower than 2.2GHz: it equals 2.17GHz. Therefore, you can easily make this CPU work at 2.2GHz by increasing its Voce a tiny bit.

For example, we used the regular Athlon XP 3000+ on Barton core with 333MHz bus in our tests. We made it work at 2.2GHz with 400MHz bus in no time at all. We didn’t even have to raise its Vcore!

As a result, we managed to investigate the performance of the upcoming Athlon XP processors with 400MHz bus, namely, Athlon XP 3200+ working at 2.2GHz and Athlon XP 3000+ working at 2.1GHz. To make this test session of some practical value for you, guys, we also included the results for the regular Athlon XP 3000+ working at 2.17GHz and supporting 333MHz bus, as well as competing products from Intel, namely, Pentium 4 3.0GHz with 800MHz bus and Pentium 4 3.06GHz with 533MHz bus.

Performance

First of all, we suggest taking a look at the Athlon XP performance with the memory, as soon as the new 400MHz bus support has been implemented. We will use Cachemem utility:

When Athlon XP moves to 400MHz processor bus, its bandwidth will get 18.5% higher: up to 3.2GB/sec. The bandwidth of the dual-channel memory subsystem used in nForce2 will grow up to 6.4GB/sec. This is exactly why the actual performance with the memory gets better: the read speed grows by 18%, the write speed – by 20%, and the copy speed – by 17%. Unfortunately, this performance growth is not enough to catch up with the Pentium 4 memory subsystems, which bus bandwidth equals 4.2GB/sec or 6.4GB/sec.

As for the memory subsystem latencies, a slight advantage here belongs to Athlon XP with 400MHz processor bus. Note that Athlon XP system owes this pretty low latency in case of DDR400 SDRAM to high-quality Corsair memory modules.

The results here illustrate very accurately the theoretical bandwidth of the bus between the CPU and the memory. Pentium 4 processor family is ahead of all, as they boast Quad Pumped Bus and a faster bus between the CPU and the chipset.

And now it’s high time we passed over to the performance of Athlon XP with 400MHz bus in real applications.

Well, no wonder happened in Business Winstone 2002 even after the shift to 400MHz bus. We can only see a slight performance increase caused by higher working core frequency. However, Athlon XP looks very good here even without 400MHz bus. The situation remains unchnaged: Pentium 4 CPUs with over 3GHz core frequency are defeated.

In the complex Content Creation Winstone 2003 benchmark the situation is different. Even Athlon XP (Barton) with 400MHz bus cannot outperform Pentium 4. However, the shift to faster bus does ensure about 5% performance growth.

During MP3 files encoding faster bus doesn’t matter for Athlon XP. This is a purely computational task, which doesn’t need any increase in the bandwidth between the processor and the memory. As a result, our hypothetical Athlon XP 3000+ with 400MHz bus falls a little behind the regular Athlon XP 3000+ with 333MHz bus because of its lower core frequency.

And for the algorithms used in the popular WinRAR archiving utility, the increase in the processor bus bandwidth is more than welcome. In particular, the shift from 333MHz to 400MHz bus provides about 12% performance growth. However, 800MHz of the new Pentium 4 and Hyper-Threading technology still help Pentium 4 3.0 to become the leader.

During MPEG-4 video encoding Pentium 4 processors are traditionally faster. The situation doesn’t change even when we take Athlon XP with 400MHz bus. The higher bus frequency doesn’t improve the performance at all here.

A similar situation can be observed during video encoding with Windows Media Encoder 9, although in this case the faster bus of Athlon XP processor tells a bit more on the overall performance.

Now let’s find out how efficient the 400MHz bus of Athlon XP processors will be in games.

Well, 3Dmark2001 SE is exactly the test where 400MHz bus of our Athlon XP is important. Thanks to faster processor bus even Athlon XP 3000+ outperforms Pentium 4 3.0 with 800MHz bus.

The newer 3DMark03 version also indicates that the faster bus provides a certain performance increase, although here it is too small to let Athlon XP beat Intel’s competitors.

CPU Score generated by the same benchmark is a nice test of the overall system performance. This parameter is very sensitive to the memory subsystems bandwidth and CPU computing capacities. And in this case faster processor bus of Athlon XP processor has a very good effect: the performance gets about 10% higher, according to this benchmark.

The same picture appears in Return to Castle Wolfenstein game. The hypothetical Athlon XP 3200+ fails to outpace Pentium 4 with 800MHz bus.

But in Unreal Tournament 2003 the leadership belongs to AMD CPUs. Faster 400MHz bus only strengthens their positions here.

In the same game in Flyby test the 400MHz bus plays the major role. Due to this bus only, the upcoming Athlon XP 3200+ outperforms Pentium 4 3.0GHz.

Now let’s have a look at the influence faster bus of Athlon XP Barton processor may have on the rendering tasks.

The results are not at all surprising. The CPU computing capacity is of No.1 importance during rendering. That is why CPUs working at higher clock rates outperform processors with lower clock frequency no matter how fast their bus is. As for the outrageously high results shown by Pentium 4 here, Intel owes them to Hyper-Threading technology, which sometimes affects the performance in multi-threading tasks quite significantly.

How well will the overclocked Barton with 400MHz bus perform in professional OpenGL applications? The answer to this question will follow from the results of SPECviewperf 7.1.

Athlon XP with 400MHz bus appeared very fast here. The only test where Pentium 4 managed to defeat the hypothetical Athlon XP 3200+ was 3dsmax-02. In all other tests the laurels were indisputably won by AMD processors. We would like to specifically stress the results of drv-09 and proe-02 tests, where faster Athlon XP bus ensures a tremendous effect.

And in conclusion the results of the synthetic CPU test from PCMark2002 benchmark set.

Conclusion

The major result of this investigation is not even the idea we got about the performance of the upcoming Athlon XP 3200+ and 3000+ processors. The most important thing is that we can state with all certainty: the industry is ready for the transition of AMD Athlon XP processors to faster 400MHz bus. ABIT NF7 2.0 mainboard and Corsair TWINX512-3200LL memory modules are an excellent proof to this point.

As for the performance level demonstrated by Barton based processors with 400MHz processor bus, the results are not surprising at all. However, let us leave the detailed discussion until the official announcement of these processors. Because the information about their clock frequencies used in this article is not official and hence can be not quite correct.

CPUs	Athlon XP 3200+ (Barton @ 2.2GHz, 400MHz PSB) Athlon XP 3000+ (Barton @ 2.1GHz, 400MHz PSB)	Athlon XP 3000+ (333MHz PSB)	Pentium 4 3.06 (533MHz FSB) Pentium 4 3.0 (800MHz FSB)
Mainboards	ABIT NF7 2.0 (NVIDIA nForce2)		ASUS P4C800 (i875P)
Memory	Corsair TWINX512-3200LL (2 x 256MB DDR400 SDRAM)
Graphics card	ATI RADEON 9700 Pro
HDD	Seagate Barracuda ATA IV, 80GB